This invention relates to devices for connecting a tie-in line or branch pipe to a carrier pipe. More particularly, this invention relates to tee connectors used in subsea applications for connecting branch pipes to carrier pipes typically used for carrying oil or gas.
It is common in the oil industry to connect a tie-in line or pipe, also referred to as a branch line, to a carrier pipe, also referred to as an export or main line. To accomplish this, tee connectors have been employed which grip and mount the pipe. Such prior tee connectors have a branch tap flange to which the branch pipe is affixed after a hole is bored into the carrier pipe through the bore of the branch tap flange. When the carrier pipe is in an environment where a connector can be welded to a pipe, this method using a suitable connector is typically employed. However, in some environments, such as when the carrier pipe is submersed undersea affixing a connector to the carrier pipe becomes more problematic.
Prior tee connectors for undersea applications employed annular seals and gripping means configured such that the annular seals where at the opposed ends of a connector, with the gripping means internal to the seals. In these tee connectors, longitudinal seals are needed which extend over the length of the connector up to the annular seals. A problem exists, however, since such tee connectors have a large pressure boundary (internal volume) where seal failure can occur.
Another problem with the prior connectors is that the connectors employ a single means for actuating the grips and seals. Hence, if the seals and grips require different amounts of pressure, such pressures cannot be independently set. Thus, for example, the grips may require an amount of pressure to engage the pipe which results in too much pressure on the seals whereby the seals extrude, thereby destroying the seals.
It can be seen that a need exists to alleviate one or more of these problems and disadvantages of prior tee connectors.